Reference for Medical Students, by Medical Students

Getting the Point – Soft Tissue Foreign Bodies

This week, I’ll be sharing a slew of handy information to keep in mind when dealing with foreign bodies in the Emergency Medicine setting. This post is also an introduction of sorts – Since taking over editor-in-chief duties from Sakib, the founder of this blog, my work thus far has been mostly behind the scenes editing. I’ve also done some back-editing on recent posts that should make scrolling through the Quickhits site while browsing topics much easier. I hope you enjoy! (PS – I apologize for any puns in advance)

Corey Warf, EiC

First, the Quickhit:

Pathophysiology

Foreign bodies in tissue generate an inflammatory response which varies in intensity based on the composition of the object: inert materials (glass, plastic, metal) generating less of a response than organic materials such as bone, spines, woody plants, or vegetative material.

Likewise, risk of infection varies based on foreign body material: inert materials are relatively low risk, while organic materials pose a much higher risk of infection.

Composition of infections often vary based on material as well: tooth fragments increase the risk of polymicrobial infections while woody materials may increase the risk of fungal infections, e.g.

Presentation and Exam

Lacerating or penetrating injuries with an object that may break, shatter, or splinter have higher odds of a foreign body being present in the wound.

Wounds deeper than 5mm or those that cannot be fully explored have a higher risk of foreign body presence.

An adult who senses a foreign body’s presence in a wound has double the risk of a retained foreign body, compared to an adult who does not sense a foreign body with a similar injury (Note: this only holds true for adults, not pediatric populations, even if verbal).

Keys to a good exam are adequate lighting, hemostasis, and anesthesia. Try to visualize the entirety of the wound. Puncture wounds can be extended with a scalpel to improve visualization.

For deeper wounds involving glass or metal, insert a closed hemostat and withdraw – scraping on the way out may indicate a retained foreign body.

Diagnosis

If a foreign body is suspected, order imaging!

Appropriate imaging studies varies based on situation – no single imaging modality is appropriate for every situation.

Radiopaque objects such as leaded glass, metal, bone, rocks, and some plastics can be detected with X-ray; however, x-ray often does a poor job with organic materials that are not hard bone.

CT scan is fairly sensitive for foreign bodies, but has the drawbacks of increased cost and radiation exposure. Also, a weird quirk of CT scan is that wood can sometimes mimic the appearance of air bubbles in soft tissue, which may confuse a foreign body (not-as-bad) with a gas-producing infection (extremely-very-hyper-bad). So keep that in mind.

Bedside ultrasound has the benefits of being quick, non-irradiating, and performable by the physician at the bedside. As an added bonus, it allows for guided removal of hyperechoic foreign bodies such as glass. However, it can be a difficult skill to master, and false positives may lead to you digging around tissue. Other hyperechoic structures (soft tissue calcifications, bones, tendons) can mask the presence of foreign bodies.

Again – there is no single best imaging study to order for all situations. Think about the injuring material and its properties. Physics may be boring, but a little bit of knowledge can go a long way.

Treatment and Disposition

Not all foreign bodies have to be removed! Step One – figure out if it even requires removal.

Good indications for removal include: toxic material; risk of infection; involvement of nerves, tendons, blood vessels or potential to migrate to those structures.

Some foreign bodies may require special removal techniques – see relevant discussion below. Foreign bodies that are in very deep tissue or embedded in hands or face may require special surgical consult or specialist follow-up.

After removal, closure depends on infection risk. Low-risk wounds can be closed with primary intent – all the good evidence shows that these wounds do not require prophylactic antibiotic use.

Wounds at risk for infection (think heavily contaminated materials, like teeth fragments) may require healing by secondary intent or delayed primary closure. However, in the absence of active infection, prophylactic antibiotic use is currently of unclear benefit at best (I guess if there were active infection, it would no longer be considered “prophylactic antibiotic use” anyway).

After discharge, appropriately inform the patient of the risk for a retained foreign body and document, document, document – don’t let them show up 6 months later with a frivolous lawsuit because they had “no idea” a piece of glass would fall out of their arm (even though you told them multiple times).

Continue reading below for further discussion:

Special Removal Techniques

Figure 1 – A common problem for the beginner.

Probably one of the sexier aspects of removing foreign bodies is busting out some of the commonly-seen techniques involved in their removal. But if you’re like Ricky Bobby, you may have no idea what to do with your hands. While I won’t go through all the techniques (as they’re typicall well-described in any EM textbook you care to pick up) I want to make some special notes on certain foreign objects and tips to avoid undue pain for your patient (and possibly yourself!)

Fishhooks

Figure 2 – What a fishhook may look like

Ah, the fishhook. I can’t think of another foreign body with a wider variety of extraction techniques. And not for good reason; the fishhook’s barb makes extraction difficult and causes pain far out-of-scale to its size. Just for the halibut, I want to mention a couple in-depth pointers to help you skate through fishhook extraction and have the procedure go swimmingly (that was the last fish pun, I swear).

The advance-and-cut technique is one of the more popular techniques out there. Some (obvious) caveats – the path of the barb point will lacerate tissues and structures in its path, so know your anatomy and what you’re advancing through before you lacerate a nerve or vascular structure. Likewise, you run the risk of further contaminating undisturbed tissue in the wake of the barb’s path. In other words, if fish or worm guts went in with the fishhook, they may not be coming out the other end.

The string-pull technique is another potential removal method, but I would use caution when applying this technique. To paraphrase Tintinalli’s – failure can mean quite a bit of pain for the patient, while success runs the risk of flinging a bloody, contaminated, sharp object across the room at high speeds.

Needles

Needle tips have the potential to break off and become left behind in soft tissue, especially in IV drug users who may not be using the most high quality equipment to begin with. If the point is accessible from the skin surface, grasp it with a pair of forceps and advance it out backwards along the path of injury. If it is too deep to grasp, make an incision with a scalpel directly on the midpoint of the needle, then grasp the midpoint and advance it back along its track, out of the skin.

Splinters

Wood is notorious for splintering and fragmenting – part of the reason it runs the risk of leaving a foreign body in the first place is why extraction is likewise so difficult. Care and precision must be taken to lift the splinter out whole, rather than rooting around for an easy-to-detect but difficult-to-localize splinter of wood. Make an incision above the splinter to lift it out whole. If it can’t be located, and isn’t near any neurovascular structures, a small block of tissue containing the splinter can be excised whole – sparing the time and frustration of trying to directly visualize a tiny fragment of wood.

Subungual splinters typically require excision of the overlying nail to remove the splinter whole. Trying to extract the splinter otherwise may leave a very painful, even more difficult to extract fragment behind.

Figure 3 – Doing things the wrong way.

Chronically retained foreign bodies

These deserve a quick discussion, because the presentation can potentially be very different from an acute presentation of a foreign body. The patient may present with chronic pain or inflammation either at a skin site or near a joint. Chronic or recurrent infections at a specific site are the other likely presentation for a chronically foreign body. These require a higher margin of suspicion because the patient may or may not recall the initial event, or may mention it only incidentally.

Chronically retained foreign bodies can cause a variety of pathologies; this includes the previously mentioned recurrent infections, but also synovitis, arthritis, scarring, or chronic pain. If the presentation for these complaints seems odd or unusual, or centers around an onset that was very sudden or associated with an injury that may have left a foreign body, consider obtaining appropriate imaging (while remembering that there is no appropriate imaging modality for all situations). Document any suspicions of a foreign body even if imaging and exam are negative. If a foreign body is found – remove as appropriate, consider a specialist in some cases as mentioned above. If a patient presents with a retained foreign body and evidence of an infection, now is the time when you would prescribe antibiotics along with removal of the foreign body.